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4 votes
Two numbers that multiply to -30 and add to 3?

User Adamesque
by
8.0k points

1 Answer

6 votes
x+y=3
xy=-30

x+y=3
minusx
y=3-x
sub
x(3-x)=-30
3x-x^2=-30
times -1 both sides
x^2-3x=30
minus 30 both sides
x^2-3x-30=0
use quadratic
for
ax^2+bx+c=0
x=
(-b+/- √(b^2-4ac) )/(2a)

1x^2-3x-30=0
a=1
b=-3
c=-30

x=
(-(-3)+/- √((-3)^2-4(1)(-30)) )/(2(1))
x=
(3+/- √(9+120) )/(2)
x=
(3+/- √(129) )/(2)
the numbers are
(3+ √(129) )/(2) and
(3- √(129) )/(2)
User Keith Hanson
by
7.8k points

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